"Campaigns get negative when candidates get desperate," Landrieu said in an ad that aired within 24 hours of Forman's attack. "We're facing the greatest rebuilding effort in history, and Ron Forman is using negative ads to divide us."

But Landrieu had no qualms about bringing up some of Forman's over-budget projects.

There have been many aggressive exchanges in the campaign for New Orleans mayor.

During a televised debate this week, contender Tom Watson, a politically savvy minister, called incumbent Mayor C. Ray Nagin a liar and said Nagin had "drowned 1,200 people" because he lacked an evacuation plan after Hurricane Katrina. Republican businessman Rob Couhig described as foolish Forman's proposal to hire a professional city manager and four deputy mayors.

Amid the campaign rhetoric, the demure Forman and the politically astute Landrieu had for the most part kept it polite -- until now.

As the race for mayor comes down to the wire, the public sparring between two longtime family friends has intensified.

The top two finishers in Saturday's election will compete in a runoff May 20.

And with many political observers predicting that Nagin will win one of the two slots, Forman and Landrieu are seen as competing for the other.

Political analysts said four other candidates, regarded as second-tier contenders, could take votes from Forman or Landrieu.

It's left to Forman and Landrieu to try to distinguish themselves, because some voters see them as having similar views. They are both Democrats with affable personalities, and their plans for rebuilding the city include ensuring flood protection; investing in social services, education and business; and combating crime.

In an interview this week, Forman -- a political newcomer -- insisted he was simply speaking the truth about Landrieu's record.

"It's interesting when you're in a campaign for the first time and you talk about a politician's record -- they don't like that," said Forman, who charged that Landrieu supported high taxes on small businesses and was lenient on crime. "We are going to continue to talk about his record."

In the same debate in which Watson criticized Nagin, Forman said many people had told him that he and Landrieu answered "too many questions alike." So he introduced advertisements that distinguished his record from the lieutenant governor's.

Landrieu mocked Forman for becoming a quick political study.

"You get into the last couple of weeks of a campaign, and you're not doing as well as you'd like, so you run negative ads," Landrieu told Forman during the debate. "Ron, you've come a long way as a politician."

The irony of the sniping is not lost on voters, who in the weeks after Katrina listened as Landrieu and Forman publicly urged each other to run for mayor.

In the early 1970s and fresh out of college, Forman worked in the administration of Landrieu's father, Maurice Edwin "Moon" Landrieu -- the city's last white mayor -- and has described the elder Landrieu as his mentor.

Forman also gave his political support to Landrieu's sister, U.S. Sen. Mary L. Landrieu (D-La.). And Mitch Landrieu consistently supported Forman's plans at the Audubon Nature Institute.

Many residents said the candidates' barbs were not constructive.

"You'd be hard-pressed to find someone who likes the negative campaigning," said Gerald Duhon, executive director of the Young Leadership Council, a nonprofit that promotes leadership through community service and does not endorse any mayoral candidate. "It's entertaining, but unfortunately I wish it wasn't the case. It's silly and embarrassing, and it's taking away from the exchange of information."

Analysts said the confrontation between Forman and Landrieu had eased some of the pressure on Nagin, whose main support is considered to come from African American Democrats.

"They are giving Nagin a pass right now because they figure he will be in the runoff," said Silas Lee, a national pollster who teaches sociology at Xavier University of Louisiana. "So they're not expending too much energy on criticizing him."

Forman supported Nagin for the last four years, but broke with him after Katrina. Forman's wife, Sally, was communications director for the mayor's office until this year.

Forman has led in some opinion polls among white voters, and analysts said Landrieu -- seen as the candidate with the strongest biracial coalition -- might have a base that could be the easiest to peck away.